(Note: At around 19 minutes we're talking about making soda with less sugar and I mentioned Splenda. I MEANT STEVIA. We do not recommend using any artificial ingredents or sweeteners. STEVIA is the only low calorie sweetener we recommend!)
Why make your own soda?
Compare the ingredients between canned grape soda and homemade natural soda:
Canned: carbonated water, high fructose corn syrup, natural flavors, tartaric acid, potassium sorbate and sodium benzoate (preservatives), citric acid, red 40, blue 1 (notice the lack of the word "grapes"?)
Homemade: Water, Cane Sugar, Fresh Ginger, Fresh Lemon Juice, Yeast
Soda first got its start by combining flavors with natural sparkling mineral water. In the late 1700s, a chemist figured out how to put carbon dioxide into water using fermented yeast. About 20 years later a Swiss scientist invented a mechanical method of carbonating water (without yeast).
Up until 1914, all drugs were basically “over-the-counter”, so pharmacists would make concoctions of drugs like cocaine and caffeine (for treatment of headaches) and mix them into flavored soda beverages to make them more palatable.
Today the majority of store-bought soda is made by injecting CO2 into water, but there are a few craft soda companies that still do natural fermentation / carbonation.
When yeast activates, it consumes sugar and releases CO2. This is why bread rises.
You want to use a yeast designed for brewing if possible - preferably a wine or champagne yeast. You should stay away from beer and lager yeasts, they can carbonate too fast and make your bottles explode. You could use bread yeast if that’s all you have, but you get a better flavor with brewing yeast. Don't try to use nutritional yeast - the cells are no longer active.
Start with good juice
Start with a juice with nothing added - no added sugar or preservatives. Citric Acid and Ascorbic Acid (Vitamin C) are ok, but make sure there are no preservatives like Sodium Benzoate or Potassium Sorbate - these will kill the yeast.
- 6 cups Concord grape juice (or 4 pounds fresh grapes if making your own juice)
- 1/2 cup freshly-squeezed lemon juice
- 1 cup water
- 8 - 14 T sugar (depending on how sweet you want your soda. Use less if starting with store bought juice)
- Pinch of salt
- 1/8 t wine or champagne yeast
If using fresh grapes, juice them in a steam juicer, or puree them and strain through a fine mesh strainer. Bottled juice is easier for the first time though.
Heat 1 cup of water enough to dissolve the sugar and salt. Let it cool - it has to be below 110°F or it could kill the yeast.
When cool add the lemon and grape juice. Pour the mixture into a clean recycled 2-liter soda bottle. Top off with cool water (if needed), leaving about 1” headspace.
Add the yeast, cap tightly, give it a good shake. Let the bottle sit at room temperature for 12-48 hours. Check it periodically, when it’s rock solid it’s fully carbonated.
Either drink it right away, or put it in the fridge to stop the fermentation process.
You can bottle your soda right after mixing in swing-top bottles, for a nicer look. The typical bottle is 16 ounces, so you’ll get about 4 swing-top bottles instead of 1 2-liter plastic bottle.
Since you’ll need to divide the yeast among 4 bottles, you’ll want to add it before pouring the juice into bottles. However, if you just add dry yeast, it won’t mix thoroughly and odds are the bottles won’t have an even amount of yeast in each. Instead:
Before dissolving the sugar, take 1 cup of juice in a mason jar and heat it to about 95°-105°F. Add the yeast, cover tightly and shake. Loosen the cover (allowing some air in) and let it sit for 30 minutes or so. You should see bubbling and foaming - the yeast is activating and reproducing.
Prepare the recipe as above. Pour the yeast liquid into the final mixture, right before you pour it into bottles.
Since you can’t squeeze the glass bottles, you can pop a lid occasionally to see if they’re carbonated. A better idea is to use a 16 ounce water bottle (so 3 glass and 1 plastic for the recipe) - when it’s solid you know the others are carbonated as well and it's time to chill.
You may like your soda a little weaker - dilute it with more water.
You can’t make a completely sugar free soda - the yeast needs something to eat to carbonate. But you can make low sugar - use a non-sweetened juice and 1T of sugar per cup of juice, then sweeten with Stevia.
Trace amounts of alcohol may be created when fermenting soda - typically less than 0.5%, about the same as kombucha.
Always open a bottle over the sink, especially if it’s a swing top bottle - if you have a twist-off cap you can slowly release the pressure, but a swing top releases all the pressure at once.